The invention relates to methods of making thermosetting multifunctional materials, especially those materials comprising at least one primary carbamate group and most particularly to multifunctional materials comprising at least one xcex2 or higher-hydroxy primary carbamate functional group.
Graft polymers have been known for use in the coatings industry as binders for thermosetting compositions. Graft polymer binders typically have a plurality of functional sites reactive with the functional sites of one or more crosslinking agents and upon cure, produce hard, durable, glossy films suitable for use in a variety of coating applications. Preferred applications include automotive primers, basecoats, and clearcoats. Such coatings may be waterborne, solventborne, powder, or combinations thereof.
The manufacture of graft polymers has typically involved the production of a base material having one or more functional sites per molecule. At least one of these functional sites must be capable of subsequent or concurrent reaction with at least one functional group of a graft moiety.
Graft copolymerization processes have traditionally been used to incorporate moieties that cannot be incorporated during the preparation of the base material. Examples of such moieties include polymers such as polyesters, polyurethanes and the like, surfactants, halogenated compounds, certain water dispersible groups such as nonionic groups, simple alkyl groups, functional groups such as beta- and higher hydroxy primary carbamate groups, including gamma-hydroxy primary carbamate groups, delta-hydroxy primary carbamate groups, and the like, the derivatives thereof, acid functional materials, epoxy functional materials, silane functional materials, siloxane functional materials and the like.
However, numerous problems occur during such prior art graft reaction processes. In particular, in the processes of the prior art, the reaction of the graft moiety and the base material results in reaction products which are reactive with one or more species, including the base material, other intermediate species, and/or the graft moiety. Such undesirable side reactions result in uncontrolled molecular weight growth, the loss of desired functionality, and/or gelation.
In addition, the uncontrollable reactivity of the functional group used as the grafting site on the base material can often limit the use of additional functionality on the base material and hinder the production of multifunctional graft materials. As a result, it has been difficult to obtain certain multifunctional graft materials using the processes of the prior art.
For example, if an epoxy group is used as the grafting site on an acrylic backbone, ethylenically unsaturated monomers having functional groups reactive with epoxy must be avoided during the polymerization of the acrylic backbone if the epoxy group results from the use of an ethylenically unsaturated monomer such as glycidyl methacrylate. Illustrative functional groups that would have to be avoided include active hydrogen containing groups such as amine functional ethylenically unsaturated monomers, acid functional ethylenically unsaturated monomers, and depending, on the polymerization conditions, hydroxy containing ethylenically unsaturated monomers.
Assuming that an acrylic backbone polymer""s functionality is limited to epoxy groups, the use of amine, hydroxy, or acid functional graft moieties will result in a variety of intermediate species which are reactive with the graft moiety, the epoxy functionality of the acrylic backbone or both. As a result, attempts to use an amine or acid functional graft moiety will often lead to uncontrolled molecular weight growth, the loss of desired functionality on the backbone, and/or gelation.
Moreover, it would be advantageous to obtain graft materials with the aforementioned advantages but which also comprise primary carbamate groups. Graft materials containing mixed functional groups such as xcex2 or higher-hydroxy primary carbamate groups would be even more advantageous.
It would thus be advantageous to provide a method of grafting that would address the deficiencies of the prior art. In particular, what is desired is a method of graft polymerization that would facilitate the production of multifunctional graft materials, especially multifunctional graft polymers wherein at least one functional group comprises a primary carbamate group, especially a xcex2 or higher-hydroxyl primary carbamate group. Such improved graft material manufacturing processes would have a decreased risk of uncontrolled molecular weight growth, the loss of desired functionality on the base material, and/or gelation.
It is thus an object of the invention to provide a method of making multifunctional graft materials that eliminates the disadvantages of the prior art.
In particular, it is an object of the invention to provide a method of obtaining a graft material having at least two functional groups that would be reactive with each other under reaction, oligomerization, or polymerization conditions. That is, the at least two functional groups on the final reaction product would normally present serious challenges with respect to side reactions if incorporated via traditional reaction, oligomerization or polymerization routes.
It is another object of the invention to provide a relatively simple and commercially feasible method of making xcex2 or higher-hydroxy primary carbamate functional materials having at least one other functional group obtained through grafting reactions, most particularly at least one hydroxyl functional urethanized grafting moiety.
These and other objects have been achieved with the methods of the invention.
In one embodiment, the method of the invention provides a simple and commercially feasible way of making multifunctional materials. The term xe2x80x9cmultifunctional materialxe2x80x9d as used herein refers to compounds, oligomers, or polymers comprising a least one primary carbamate group and at least one grafting moiety (cii) per molecule on average. In a most preferred embodiment, xe2x80x98multifunctional materialxe2x80x99 refers to compounds, oligomers, or polymers comprising one or more xcex2 or higher hydroxy primary carbamate groups and one or more hydroxyl functional urethanized grafting moieties (cii) per molecule on average.
It is an aspect of the method of the invention that a base material P comprising two or more cyclic carbonate groups (bi) per molecule on average must undergo two different reactions, either successively or simultaneously. More particularly, at least one of the cyclic carbonate groups on average per molecule of the base material P must undergo a reaction (A) with ammonia. At least one other cyclic carbonate group of the base material P per molecule on average must undergo a reaction (B) with a grafting material (c).
Grafting material (c) comprises at least one amine group (ci) and a grafting moiety (cii). The amine group (ci) is selected from primary amines, secondary amines, and mixtures thereof. Grafting moiety (cii) may be a material, oligomer, or polymeric in nature. Grafting moiety (cii) will generally comprise a backbone which may be aliphatic, cycloaliphatic, aromatic, unsaturated and mixtures thereof. Grafting moiety (cii) may also contain hetroatoms such as O, S, N, Si, and the like which may be in the form of ether groups, ester groups, urethane (non-primary carbamate) groups, urea groups, mixtures thereof and the like. Grafting material (c) can possess additional functional groups (ciifg) that are not reactive towards a cyclic carbonate group under the conditions of reactions (A) or (B). Non-limiting examples of additional functional groups (ciifg) are carbamate groups, acid groups, hydroxy groups, ethylenically unsaturated groups, ester groups, ether groups, urethane groups, urea groups and mixtures thereof.
In another embodiment, the method of the invention provides multifunctional waterborne materials, especially xcex2 or higher -hydroxy primary carbamate functional materials. In this embodiment, the at least one grafting moiety (cii) is selected from secondary amines, tertiary amines, acid groups, salted acid groups, and nonionic groups. In addition, it is an aspect of this embodiment of the invention that if the at least one grafting moiety (cii) is a secondary or tertiary amine, or if the at least one grafting moiety (cii) is an acid group and the reaction of material P with ammonia proceeds before the reaction of material P with grafting material (c), the method of the invention will further comprise reacting the grafting moiety (cii) with one or more salting agents (f) to provide a salted site (cii*) which facilitates the dispersion of the final multifunctional material into water.
The waterborne multifunctional materials of the invention will generally have the structure:
(Cgraft)ixe2x80x94Pxe2x80x94(CNH3)j.
In this formula, P is a hydrocarbon-based material selected from the group consisting of compounds, oligomers, and polymers, and has a number average molecular weight PMW. Cgraft is the reaction product of ammonia and a cyclic carbonate functional group and has at least one structure selected from the group consisting of of formulas (I), (II) and (III): 
wherein Cxe2x80x2 is a saturated carbon having substituents selected from hydrogen and alkyl groups of from one to six carbons, R is hydrogen or an alkyl group of from one to six carbons, and cii is a grafting moiety selected from secondary amines, tertiary amines, acid groups, salted acid groups, nonionic groups, and mixtures thereof. i and j may be the same or different and will each be a number from 1 to about 49. CNH3 is the reaction product of ammonia with a cyclic carbonate functional group and will have a structure selected from the group of formulas (I), (II) and (III): 
wherein Cxe2x80x2 is a saturated carbon having substituents selected from hydrogen and alkyl groups of from one to six carbons, and n is a number from 0 to 6. When
WV1=PMW÷(i+j) and WV2=PMW÷(i),
the waterborne multifunctional materials of the invention will be electrodepositable if WV1 is a number from 500 to 2000 and WV2 is a number from 320 to 1000; water dispersible if WV1 is a number from 400 to 800 and WV2 is a number from 450 to 1500; and water soluble if WV1 is a number less than 600 and WV2 is a number from 320 to 2500.
The invention further provides a method of making multiple multifunctional acrylic materials from a single precursor material or limited starting reactants. This method requires providing an ethylenically unsaturated monomer mixture (a) comprising two or more monomers (ai) having at least one cyclic carbonate group and the structure 
In this formula L is a linking group selected from aliphatic groups, cycloaliphatic groups, aromatic groups and mixtures thereof of from one to seven carbons, n is a number from zero to six, and R is either hydrogen or an alkyl group of from one to six carbons.
The method then requires polymerizing the monomer mixture (a) to make an acrylic backbone polymer (b) comprising two or more cyclic carbonate functional groups (bi) and then subjecting a first portion of the acrylic backbone polymer (b) to successive or simultaneous reactions of reaction (A) with a first grafting material (c) and reaction (B) with ammonia, to make a first multifunctional material of the formula: 
wherein A is the residue resulting from the polymerization of ethylenically unsaturated monomers which does not contain a cyclic carbonate group, L is a linking group selected from aliphatic groups, cycloaliphatic groups, aromatic groups and mixtures thereof of from one to seven carbons, and p is number of from 0 to 5.
CNH3 is the reaction product of ammonia with a cyclic carbonate functional group and will have a structure selected from the group of formulas (I), (II) and (III): 
wherein Cxe2x80x2 is a saturated carbon having substituents selected from hydrogen and alkyl groups of from one to six carbons, and n is a number from 0 to 6.
Cgraft is the reaction product of ammonia and a cyclic carbonate functional group and has at least one structure selected from the group consisting of of formulas (I), (II) and (III): 
wherein Cxe2x80x2 is a saturated carbon having substituents selected from hydrogen and alkyl groups of from one to six carbons, R is hydrogen or an alkyl group of from one to six carbons, and cii is a grafting moiety selected from aliphatics, cycloaliphatics, polyurethane oligomers and polymers, nonionic groups, polyalkyldienes, triazines, hindered amine light stabilizers, aromatic groups, ionic groups, and mixtures thereof.
k is from 1 to 95% by weight of the total sum of k, l, and m. l, is from 0 to 50% by weight of the total sum of k, l, and m, and m is from 1 to 95% by weight of the total sum of k, l, and m.
After this first multifunctional material is produced, the method requires that one or more different portions of the acrylic backbone polymer (b) be subjected to successive or simultaneous reactions of reaction (A) with different grafting materials (c) and reaction (B) with ammonia, to make multiple multifunctional material of the formula: 
wherein all variables are as defined above except that cii is different for each additional multifunctional material.
The multifunctional materials made by the methods of the invention are useful as a film-forming components in curable film-forming compositions, especially curable coating compositions, whether solventborne, liquid solvent free coatings, waterborne, electrodeposition, powder, or powder slurry. Automotive applications requiring an optimum balance of finished film properties will particularly benefit from the use of the primary carbamate multifunctional materials made by the method of the invention. Finished film-properties that improve with the use of the claimed multifunctional materials include etch resistance, scratch and marring resistance, UV durability, chip resistance, adhesion, and/or the like.